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BQ27542-G1: Ra table has been updated large value after test

user4576477
Prodigy 90 points
Part Number: BQ27542-G1
Other Parts Discussed in Thread: GPCRA0

Hi all,

I have a problem that Ra table has been updated large value after charge/discharge test, the failure is 11/80=13.75%. There are three phenomanon as below.

1. SOC 80% jump to 100% during charge.

2.  After fully charge, I still charge pack many hours and found SOC 100% jump to 91%, and sometimes I remove charger the SOC went down, either. 

3. SOC changed from 92% to 100% when I replug battery.

The update status=06 and calibration done before test. Mean while, I compared these packs and I found Ra table has been updated large value and Qmax smaller than good packs. And I do learning again, these packs problem is solve. What reasone may cause Ra table has been updated large value?

BQ27542-G1 five packs compare.xlsx

  • 0
    TI__Guru* 76230 points
    Hi

    Do you have smoothing enabled. If no, you willl need to enable it, that will prevent soc from dropping from 100% to 90% if the charger is removed.
    Secondly, when you did your learning, what chem id did you use? The problem you are seeing is symptomatic of using a chem id that isn't a good match for your battery chemistry.
    Thirdly, to address the jumps to 100%, i would recommend using our online tool gpcRa0 to calculate the Ra0 value of your resistance table. This will help mitigate the jumps to 100%.
    Finally, the increase in resistance in the Ra table might be due to board trace impedances between your battery and your board. Is your battery connected to the board using long wires. Did you use kelvin connections for the battery connection?

    thanks
    Onyx